Ion exchange coupled biomineral self-sacrificial template synthesis of N-enriched porous carbon as robust electrocatalyst for rechargeable Zn-air battery

To realize the commercialize of rechargeable Zn-air battery(RZAB),developing metal-free bifunctional electrocatalysts with satisfactory activity for oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)is one of the emerging issues.Herein,a prawn shells-derived N-enriched porous carbon(PSNC)is synthesized via an ion exchange coupled biomimetic selfsacrificing template strategy.The resulting PSNC displays unique functional components,including the interconnected macro-meso-micropores structure to shorten charge and mass transfer pathway,high content of pyridinic and graphitic nitrogen to construct rich catalytic active site and improve conductivity.As electrocatalysts in alkaline condition,the optimized PSNC-0.8 achieves excellent bifunctional catalytic propriety with a narrow potential gap(ΔE)value of 0.80 V.Meanwhile,PSNC-0.8-based RZAB displays a high peak power density of 176.5 mW·cm^(-2)and considerable cycling durability with a small battery efficiency delay of 6.5%after 480 cycles(320 h).This study enlightens a simple and effective conception to design high-performance metal-free bifunctional electrocatalysts from seafood waste.

ZIF-8-derived Fe-C catalysts:Relationship between structure and catalytic activity toward the oxygen reduction reaction

The oxygen reduction reaction(ORR)activity of carbonized ZIF-8(CZ)and its Fe-doped derivatives,CZ-A(doped with ammonium iron(II)sulphate)and CZ-B(doped with iron(II)acetate),were examined in both acidic(0.5 M H_(2)SO_(4))and basic(0.1 M KOH)electrolytes using a rotating disk electrode setup.These data show that the ORR activity of the Fe-doped catalysts is higher than that of pure CZ,with a higher activity in basic than acidic electrolyte.Extensive materials characterization highlights important differences in the sample crystallinity,morphology,porosity,and chemical composition as a function of the deployed precursor.The performance of the prepared catalysts is also impacted by the Fe precursor selection,highlighting the importance of such synthetic parameters in controlling the density and identify of Fe-Nx active sites.These results demonstrate the potential application of Fe-doped carbonized ZIF-8 catalysts for the ORR in basic electrolyte and offer important knowledge for the future design of non-precious metal fuel cell electrocatalysts.

Recent advances and perspectives on prelithiation strategies for lithium-ion capacitors

Lithium-ion capacitors(LICs),consisting of a capacitor-type material and a battery-type material together with organic electrolytes,are the state-of-the-art electrochemical energy storage devices compared with supercapacitors and batteries.Owing to their unique characteristics,LICs received a lot of attentions,and great progresses have been achieved,especially in the exploration of cathode and anode materials.Prelithiation techniques are regarded as indispensable procedures for LICs systems,which can compensate for the initial irreversible capacity loss,increase the Li^(+)concentration in the electrolyte,raise the working voltage and resolve the safety and cycle stability issues;however,its research progress is slow,and there is not enough attention until now.In this overview,we look into the ongoing processes on the recent development of prelithiation technologies,especially in organic electrolyte consumption-type LICs.In particular,some prelithiation strategies for LICs are summarized and discussed in detail,including the ex situ electrochemical method,in situ electrochemical method,and cathode prelithiation additives method.Moreover,we propose some unresolved challenges and prospects for prelithiation technologies from the basic research ideas and future key research directions.This work aims to bring up new insights to reassess the significance of premetallation strategies for advanced hybrid-ion capacitors based on the currently proposed prelithiation strategies.